The invention relates to a mechanism for registering a sheet relative to a station and, more specifically, to a registration mechanism particularly suitable for a sheet of film that is to be fed to an imaging station for exposure by a laser scanning system.
Sheet registration mechanisms of various kinds are known in the art. For example, U.S. Pat. No. 4,660,819, issued Apr. 28, 1987 in the names of C. Allocco et al, discloses a sheet registration device in a document handler of the kind used with electrographic copying apparatus wherein a set of document sheets are recirculated one or more times from the tray to a copying position and then returned to the tray. The handler of the patent has a tray surface on which sheets rest, and a sidewall or guide along one side edge of the tray surface terminates in an inclined ramp at the surface. A similar inclined ramp is provided on the other side of the tray. The two ramps are generally parallel to each other along opposite side edges of the tray. These ramps assist in registration of the document sheets in a corner of the tray prior to feeding of the sheets to the copying position.
Known sheet registration mechanisms may require a force other than gravity to be used for proper positioning of the sheet in the registration mechanism. In the above mentioned patent, for example, an air knife provides a jet of air which assists in locating the sheet on the tray surface. Also, known registration mechanisms require delivery of sheets to the mechanism from only one side, and such can limit the use of the mechanisms to specific kinds of apparatus.